Improvement in hand-pi eces for dental engines



i Y R. B. DONAL DSONV Hand-Piece for Dental-Engines.

No. 222,181. Patented Dec. 2,1879.

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I 1 A I 4 N.FETERS. PHOTO-UTHOGRAPniR. WASHINGTON. D C.

ROBERT E. DONALDSON, OF WASHINGTON, DISTRICT or COLUMBIA.

lMPROVEMENTllN HAND-PIECES FOR DENTAL ENGINES.

Specification forming part of Letters Patent No. 222,181, dated December'2, 1879; application filed October 24, 1879.

the following is a specification.

One object of my invention is to furnish an improved hand-piece, adaptedto secure firmly tools having smooth round shanks, and admit of theirready and convenient removal from the'rotating mandrel or chuck of thehandpiece by the operator. p

Anotherobject is to provide a simple and efiective means whereby thewear of the bearin gs upon which the mandrel or chuck revolves can betaken up orcompensated for, so that the chuck can always be kept so asto run freely and steadily, however much the bearings may be wornbyfriction.

i I The accompanying drawings will show the different parts and theirapplication comprising my invention.

Figure 1 represents an external view of the hand-piece as improved by mewhen ready for attachment to the dental engine. Fig. 2represents alongitudinal central section of the same. Fig. 3 represents a view ofthe revolving mandrel or tool-chuck, which is socketed atone end, asusual, for the reception of the round shankof the operating-tool, andproperly formed at the other end for attachment to the flexible cable ordriving-shaft of the den tal engine, which is to operate it. Figs. 4, 5,6, 7, and 8 represent detail parts to be herein after referred to andexplained.

To enable the operator to secure the operating-tool quickly, asily,yetfirmly, in the socket of the chuck or mandrel of the hand-piece andremove. it with equal facility, in order to substitute a different toolwhile operating upon the'teetli, has always been among the mostimportant of the many considerations involved in the constructionand useof dental engines. Many different devices have been invented andpatented for this particular purpose, but, with few exceptions, thesetool-locking devices have required a 1ug,a notch, or some otherpeculiarity of construction at the end of thetoolshank, which wouldprevent thetools being used in any'other hand-piece thanthe one providedwith a lock or catch specially adapted to their peculiar formation. Thusdentlsts who use the hand-piece of one manufacturer cannot use theburrs, drills, and otherengineinstruments of other manufacturers,because of their shanks being shaped differently. The diameter andlength of the shank are, however, the same in the instruments'ot' allthese different manufacturers. It is, therefore, very desirable to havea hand-piece in which the instruments of any or all of them can be used.This can be accomplished only by-having a clamp or clutch which willsecure firmly a plain round shank in the socket of the chuck or mandrelof the hand-piece. Two or three devices of more or less value havealready been invented and patented for this purpose, but differingradically from my invention, which involves what I believe to be theapplication of a new principle in this connection. 7

By taking advantage of levenpower, which has never before, to myknowledge, been used in this connection, I am enabled to bring apowerful pressure to bear upon the plain round shank of theoperating-tool when within the socket, thus securing it so firmlytherein as to resist any force which in practical use would tend toloosen or withdraw it.

In order to overcome the difficulty which would be experienced from thespringing or yielding of a solid lever of the length and limitedthickness necessary in this connection, I make use of a tube or sleeveto subscrve the purposes of a lever. This possesses the advantages ofbeing thin and light, occupies but little space, and yet is, whenproperly tempered, very strong and unyielding, giving the positivepressure required- This tubedever (a separate view of which is given inFig.5) surrounds, andis pivoted upon, the chuck or mandrel, the chuckbeing enough reduced in size in each direction from the point a, Fig. 3,where the pivot is inserted, to allow a free movement in the direction,and for the space required, of the long and short ends of the lever. v

The clamp 4:, Fig. 6, is made of steel and hardened, and is fitted so asto move freely 1n a longitudinal slotfzin the chuck or mandrel. (Shownat b, Fig. 6.) v

v The side of the clamp which'is intended to embrace the tool-shank-isgrooved to fit the round of the shank. The opposite side, d. is roundedto conform to the inner surface of the tube-lever, the short end ofwhich lever presses upon it, forcing the clamp firmly chuck or mandrel,the lever moving freely upon the pivot. This small lever is operated bya spring, 0, which is screwed or riveted to the chuck or mandrel at thepoint f, the free end of the spring bearing upon the lever 61 at thepoint 9, thus causing the short end of said lever to press upon theinner surface of the long end of the main or tube lever at h, forcingthis end of the tube-lever in a direction away from the body of themandrel, and, as a necessary consequence, forcing the opposite or shortend down upon the clamp t.

For the purpose of removing the tool which has been clamped, the longend of the lever d is inclined or raised from the mandrel on the sideopposite to that upon which the spring bears, when all the several partsare in position. This inclined end is operated upon by a steel thimble,70, which is fitted to-and slides freely upon the inner surface of theoutside casing, Z. This steel thimble is moved forward or backward bymeans of two fingerpieces, at m, (the external surfaces of which areroughened,) which are screwed fast to the outer surface of the thimble7c, and move in longitudinal slots cut through the outer case,

I. When moved backward by pressure upon these finger-pieces the innersurface or bore of the thinible (which is slightly rounded from withinoutward at the end) impinges upon the inclined end of the lever 01,pressing it down toward the chuck or mandrel, thus relieving thepressure of the short end of this lever upon the main or tube-lever,and, as a necessary consequence, relieving at the same time the pressureof this main lever upon the clamp confining the tool in the socket ofthe chuck.

By this double-lever arrangement but little force is necessary torelieve the tool, notwithstanding the power with which it has beenclamped, a very slight pressure upon the finger-pieces being all that isrequired to loosen the tool in the socket. A reverse motion of thefinger-pieces will, of course, allow the spring to act normally upon thelever and again clamp the tool. I

The tube surrounding the mandrel and pivoted thereon to serve as alever, I consider the most important part of my invention; and

the tube-lever may be operated upon directly by a spring without theintervention of an-additional lever; and this spring could be soconstructed that the sliding thimble 7a, when moved back, would pressdirectly upon it, and thus relieve the pressure upon the tube-lever whenthe tube is to be removed. Or a spiral spring surrounding the rearportion of the mandrel could be used to force under one side of the longend 'of the tube-lever a properlyconstructed thimble, (one side beinginclined,)

thus forcing the short end of said lever down upon the clamp.

The second part of my invention consists of a sliding collar, a separateview of which is given in Fig. 4., which is fitted to and moves easilyupon the outside of the rear end of the hand-piece to which the casingis attached, and furnished with a set-screw, o, by means of which it canbe secured firmly in any desired position within the range of itsmovement. The front end of the collarforms the shoulder, against whichthe outside case is screwed when the parts are in position, and it isintended to regulate or adjust the chuck or mandrel when it has becometoo loose from the wear upon its bearings.

Fig. 8 represents a view of the rear portion of the hand-piece providedwith a screw portion, 19, to which theouter casing is intended to beattached by an inside or female screw, and showing the regulating-collarn in position.

In my hand-piece the screw portion]? is made a little longer than in theordinaryhan d-pieces, and is bored, as usual, for the reception of thereduced end of the chuck or mandrel to which the flexible cable ordriving-shaft isattached. The shoulder of the mandrel (shown at s, Fig.3) bears upon the end of this screw, which thus forms one of thebearings upon which the mandrel revolves. The other bearing is withinand against the steel nib q, the bore of which is conformed to theslightly-tapering end of the mandrel, as shown atr. This steel nib,which is attached to and forms a part of the outside case, extends alittle beyond the socketed end of the mandrel whichrevolves within it,so that the oil with which the bearings are lubricated may not workoutupon the exterior of the nib or upon the exposed portion of thetool-shank.

To adjust the mandrel or chuck when it has.

become too loose from the wear caused by friction, the set-screw o isloosened and the ad-' the chuck or mandrel can, in a few moments andwithout taking the case apart, beadjusted readily and perfectly, and canbe kept so as to run true, however much it may have become worn by longusage.

I am aware that the use of a movable adjusting-collar, in connectionwith other parts of a dental hand-piece, is not new, and therefore I 'donot broadly claim the combination of an adjustable collar with theothermechanism of a hand-piece but I believe myself to be the first to applyand combine a movable adjusting-collar with a set-screw inserted in itand arranged to press upon a flattened surface of the rear section ofthe hand-piece, thus holding the collar more securely in position andwith less liability to be accidentally moved than by those methods ofconstruction heretofore in use; and it is to this particular combinationof the set-screw inserted in the adjustable collar and acting upon aflattened surface of the rear portion ofthe hand-piece, as above setforth, that my invention and claim are limited.

Having thus described my invention, What I claim, and desire to secureby Letters Patcut, is-- 1. In the hand-piece of a dental engine, a tubesurrounding and being pivoted to the tool-chuck or mandrel to serve as alever and hearing at the short end on the tool-clamp, the long end beingoperated by another lever actuated by a spring or by other suitablemeans, substantially as hereinbefore set forth and described.

2. In the hand-piece of a dental engine, the tube or sleeve pivoted andserving as a lever, in} combination with an additional lever and slidingthimble for operating the same, substantially as hereinbeforeset'forth.

3. In the hand-piece of a dental engine, the combination of thetool-clamp, the tube-lever, the small lever operated by a spring andhaving an inclined end, and the thimble having finger-pieces attachedand movable in slotsin the outside case, substantially as hereinbeforeset forth.

4;. In the hand-piece of a dental engine, the combination of the mandrelor toolchuck having one bearing against the screw in the rear portion ofthe hand-piece, and the other in the 'nib or end portion of the outercase, and the sliding collar with a set or look screwpassing throngh itand acting upon the flattened surface of the rear section of thehand-piece to secure the collar in position for adjusting the mandrelwhen the bearings have become'worn by friction, substantially ashercinbefore set forth.

ROBERT E. DoNALnsoN.

WVitnesses I JOHN T. O. CLARK, M. F; THOMPSON.

